diff options
Diffstat (limited to 'Linux-PAM/modules/pam_pwdb/pwdb_chkpwd.c')
| -rw-r--r-- | Linux-PAM/modules/pam_pwdb/pwdb_chkpwd.c | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/Linux-PAM/modules/pam_pwdb/pwdb_chkpwd.c b/Linux-PAM/modules/pam_pwdb/pwdb_chkpwd.c new file mode 100644 index 00000000..36c248ef --- /dev/null +++ b/Linux-PAM/modules/pam_pwdb/pwdb_chkpwd.c @@ -0,0 +1,221 @@ +/* + * $Id: pwdb_chkpwd.c,v 1.4 2001/12/09 21:44:58 agmorgan Exp $ + * + * This program is designed to run setuid(root) or with sufficient + * privilege to read all of the unix password databases. It is designed + * to provide a mechanism for the current user (defined by this + * process' real uid) to verify their own password. + * + * The password is read from the standard input. The exit status of + * this program indicates whether the user is authenticated or not. + * + * Copyright information is located at the end of the file. + * + */ + +#include <security/_pam_aconf.h> + +#ifdef MEMORY_DEBUG +# undef exit +# undef strdup +# undef free +#endif /* MEMORY_DEBUG */ + +#include <stdarg.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <syslog.h> +#include <unistd.h> + +#include <security/_pam_macros.h> + +#define MAXPASS 200 /* the maximum length of a password */ + +#define UNIX_PASSED (PWDB_SUCCESS) +#define UNIX_FAILED (PWDB_SUCCESS+1) + +#include <pwdb/pwdb_public.h> + +/* syslogging function for errors and other information */ + +static void _log_err(int err, const char *format, ...) +{ + va_list args; + + va_start(args, format); + openlog("pwdb_chkpwd", LOG_CONS|LOG_PID, LOG_AUTH); + vsyslog(err, format, args); + va_end(args); + closelog(); +} + +#define PWDB_NO_MD_COMPAT +#include "pam_unix_md.-c" + +static int _unix_verify_passwd(const char *salt, const char *p) +{ + char *pp=NULL; + int retval; + + if (p == NULL) { + if (*salt == '\0') { + retval = UNIX_PASSED; + } else { + retval = UNIX_FAILED; + } + } else { + pp = _pam_md(p, salt); + p = NULL; /* no longer needed here */ + + if ( strcmp( pp, salt ) == 0 ) { + retval = UNIX_PASSED; + } else { + retval = UNIX_FAILED; + } + } + + /* clean up */ + { + char *tp = pp; + if (pp != NULL) { + while(tp && *tp) + *tp++ = '\0'; + free(pp); + pp = tp = NULL; + } + } + + return retval; +} + +int main(int argc, char **argv) +{ + const struct pwdb *pw=NULL; + const struct pwdb_entry *pwe=NULL; + char pass[MAXPASS+1]; + int npass, force_failure=0; + int retval=UNIX_FAILED; + + /* + * we establish that this program is running with non-tty stdin. + * this is to discourage casual use. It does *NOT* prevent an + * intruder from repeatadly running this program to determine the + * password of the current user (brute force attack, but one for + * which the attacker must already have gained access to the user's + * account). + */ + + if ( isatty(STDIN_FILENO) ) { + _log_err(LOG_NOTICE + , "inappropriate use of PWDB helper binary [UID=%d]" + , getuid() ); + fprintf(stderr, + "This program is not designed for running in this way\n" + "-- the system administrator has been informed\n"); + exit(UNIX_FAILED); + } + + /* + * determine the current user's name: + */ + + retval = pwdb_start(); + if (retval != PWDB_SUCCESS) { + _log_err(LOG_ALERT, "failed to open pwdb"); + retval = UNIX_FAILED; + } + if (retval != UNIX_FAILED) { + retval = pwdb_locate("user", PWDB_DEFAULT, PWDB_NAME_UNKNOWN, + getuid(), &pw); + } + if (retval != PWDB_SUCCESS) { + _log_err(LOG_ALERT, "could not identify user"); + while (pwdb_end() != PWDB_SUCCESS); + exit(UNIX_FAILED); + } + if (argc == 2) { + if (pwdb_get_entry(pw, "user", &pwe) == PWDB_SUCCESS) { + if (pwe == NULL) { + force_failure = 1; + } else { + if (strcmp((const char *) pwe->value, argv[1])) { + force_failure = 1; + } + pwdb_entry_delete(&pwe); + } + } + } + + /* read the password from stdin (a pipe from the pam_pwdb module) */ + + npass = read(STDIN_FILENO, pass, MAXPASS); + + if (npass < 0) { /* is it a valid password? */ + _log_err(LOG_DEBUG, "no password supplied"); + retval = UNIX_FAILED; + } else if (npass >= MAXPASS-1) { + _log_err(LOG_DEBUG, "password too long"); + retval = UNIX_FAILED; + } else if (pwdb_get_entry(pw, "passwd", &pwe) != PWDB_SUCCESS) { + _log_err(LOG_WARNING, "password not found"); + retval = UNIX_FAILED; + } else { + if (npass <= 0) { + /* the password is NULL */ + + retval = _unix_verify_passwd((const char *)(pwe->value), NULL); + } else { + /* does pass agree with the official one? */ + + pass[npass] = '\0'; /* NUL terminate */ + retval = _unix_verify_passwd((const char *)(pwe->value), pass); + } + } + + memset(pass, '\0', MAXPASS); /* clear memory of the password */ + while (pwdb_end() != PWDB_SUCCESS); + + if ((retval != UNIX_FAILED) && force_failure) { + retval = UNIX_FAILED; + } + + /* return pass or fail */ + + exit(retval); +} + +/* + * Copyright (c) Andrew G. Morgan, 1997. All rights reserved + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, and the entire permission notice in its entirety, + * including the disclaimer of warranties. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * ALTERNATIVELY, this product may be distributed under the terms of + * the GNU Public License, in which case the provisions of the GPL are + * required INSTEAD OF the above restrictions. (This clause is + * necessary due to a potential bad interaction between the GPL and + * the restrictions contained in a BSD-style copyright.) + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + */ |